Key-driven calculating machine



5 Sheets-Sheet l Attorneys 3 INVENTOR:

V Turck 3" J. A. V. TURCK KEY-DRIVEN CALCULATING MACHINE Joseph A.

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@%@@@@W @@@@Q@@@@ Q? @@@@@@@@g@t Original Filed Nov. 22, 1949 Feb. 10, 1953 Feb. 10, 1953 J. A. v. TURCK KEY-DRIVEN CALCULATING MACHINE 5 Sheets-Sheet 2 Original Filed NOV. 22, 1949 m mfli INVENTOR. JZsqapkfl M77 We)! 2 km), W 7% far eys Feb. 10, 1953 J. A. v. TURCK 2,628,026

KEY-DRIVEN CALCULATING MACHINE Original Filed Nov. 22, 1949 5 Sheets-Sheet 6 INVENTOR: Joseph A. V. Turck a 7. R a 6 0a 7 m m m7 8 w i @w. 1 4% s mmri w h S 5 W/./ Y M H C A M mm mm Tm .C V .0 N w I w w K Feb. 10, 1953 Original Filed Nov. 22, 1949 Patented Feb. 10, 1953 KEY-DRIVEN CALCULATING MACHINE Joseph A. V. Turck, Miami Beach, Fla., assignor to Felt and Tarrant Manufacturing Company, a corporation of Illinois Original application November 22, 1949, Serial No. 128,741. Divided and this application May 26, 1950, Serial No. 164,435

10 Claims. 1

This invention relates to improvements in calculating machines, and more particularly to improvements in the key-driven type of calculating machine where actuation achieved by the downward depression of a key stores power in springs to give additive degrees of action on the up or return stroke of theactuating mechanism.

It is the general object of this invention to produce an improved'key-driven calculating machine.

It is a more specific object of the invention to provide a more desirable distribution of the manual power required forthe actuation of a keydriven calculating machine.

It is the further object of the invention to produce a calculating machine of the type described in the preceding paragraph in which the length of the machine from front to rear is reduced.

Another object of the invention is to produce new and improved control means for the compound lever system disclosed in my pending application, Serial No. 696,517.

It is a more specific object of the invention to produce a key-driven calculating machine having an actuating mechanism including a lever contacted and operated by the keys to pivot a swingably fulcrumed link in turn connected to a bell crank lever linked to the sector gear which operates the accumulator mechanism, with such actuating mechanism serving to provide a more even distribution of force required to depress a key among the various ordinal keys.

Other and further objects of the invention will become apparent from the following description of the preferred embodiment illustrated in the accompanying drawings, in which:

Fig. 1 is a plan View of a key-driven calculating machine embodying the features of the invention.

Fig. 2 is a front to rear sectional view taken substantially on the line 2-2 of Fig. 1 and showing details of the actuating mechanism for one of the ordinal columns of keys.

Fig. 3 is a front to rear sectional View taken at the right hand side of the machine and taken substantially along the line 33 of Fig. 1.

Fig. 4 is a side view of the ordinal actuating mechanism as viewed from the left hand side showing the mechanism set for additive or positive operation.

Fig. 5 is a view similar to Fig. 4 but showing the actuating mechanism set for a subtractive or negative operation.

This application is a division of my copending case, Serial Number 128,741, filed on November 22,

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiment with the understanding that the present description is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodimentillustrated. The scope of the invention will be pointed out in the appended claims.

The machine selected to illustrate the invention is similar in many respects to the machine disclosed and claimed in my said copending application, Serial No. 696,517. The machine of this invention is equipped with an accumulator mechanism 2| (Fig. 2) of the general type disclosed in my prior Patent No. 1,357,748. The mechanism includes a register comprising a plurality of denominational numeral wheels 22 each with its associated carrying mechanism for carrying over the tens from a lower denominational to a higher denominational numeral wheel. The accumulator mechanism is operated through an actuating mechanism 23 hereinafter described in detail, such operation being effected through the medium of digital keys 24. One column of keys is provided for each denominational order of the accumulator mechanism, there being 9 of the keys 24 in each column numbered 1-9 beginning at the front of the machine. The numeral wheels 22 and other elements of the accumulator mechanism are mounted upon a frame 25 supported to rock about the axis of the numeral wheels to engage and disengage the driving connection between the accumulator mechanisms and their associated actuating mechanisms. Zeroizing mechanism is adapted for operation-by means of a hand lever 26 for swinging the frame 25 to the disengaged position in which the accumulator mechanism is cleared or zeroized.

In the exemplary machine shown the keys 24 are mounted in a key frame 21 forming the top wall of a casing 28 within which the various mechanisms are supported by skeleton frame members or partitioned plates 29. Windows 30 in the top of the casing adjacent the front end thereof expose the numeral wheels to view. As shown in Fig. 1, an additional window 30".is provided to to the left of the window for the highest denominational numeral wheel to accommodate an overflow numeral wheel 22'.

As herein shown, the key frame 21 is formedof generally rectangular plates 3|, 32, 33 and 34 suitably secured together and held in parallel spaced relationship by posts 35. Each of thekeys -;key either 2 or F7, etc.

24 is provided with an elongated fiat stem 36 adapted to extend through aligned slots in the frame plates for cooperation with the actuating mechanism 23. The keys are yieldably urged upwards by individual springs 31 mounted on lugs 38 struck up from the plate 33. The free ends of the springs engage in notches formed in the edges of the stems 36 so as to lie crosswise of the slots in the frame plates 32 and 33 and thus serve additionally to define the upper and lower limit positions of the keys.

Each key 26 when depressed serves to impart a predetermined degree of digital actuation to the accumulator mechanism as indicated by appropriate rotation of the numeral wheel 22 of the denominational order with which the depressed key is associated. Thus each row of keys is adapted to impart rotation to an accumulator actuating pinion 4! (Fig.2) journalled on a cross shaft 42 that extends across the machine and is .supported by the frame members 29. Rotation of the pinion il in one direction is transmited through an internal-ratchet mechanism to a combined lantern wheel and accumulator gear 52 also iournalled on the shaft 42. The lantern wheel gear is arranged to drive the associated numeral wheel 22 through the medium of a carrying gear and intermediate gear and a pinion,

all of thegears being carried by the rock frame 25.

Carrying mechanism is provided in each denominational order of the accumulator mechanism for imparting a digital unit of actuation thereto'e'achtime that a tens transfer is to take place from a'lower to a higher denominational order of the accumulator. This mechanism is shown and described in my prior patent No. 1,357,748 to which reference may be had for a complete description of the construction and mode of operation.

In carrying out the invention the actuating mechanisms 23, 'by'whic'h the movements of the keys Mare transmitted to the accumulator mechanisms, are constructed and arranged so that the o'perationof each key may beregistered either as a positive value for use in addition or multiplication or a negative value for use in subtraction or division. More specifically, the actuating mechanisms are so constructed and arranged that they may be selectively set to transmit to the associated numeral wheel of the accumulator mechanism upon depression of a key a degree of movement'suflicient to register either the numerical Value of the key or in the units order, the complement of ten, and in other orders the nines 'complementofthe key value. Thus in each ordinal column of keys, except the first, the actuat- "ing mechanisms may beset so that thedepression :of the' 1'key*will register either .1 or 8,'the 2 In the first ordinal columnofkeys the-selective setting of the actuating mechanism automatically conditions the 1 key to register either 1 01"9, the 2 key either 2 or 8, etc. Since negative values maybe registered for subtraction or division by depressing the same Ekeys usedzfor registering positive values for addiztion, the keys may be designated by a single The 9 key in each denominational order'carries the figures 9 and 0. n subtraction, of coin se, the Os are not used. In division the sare not used but Os appearing anywhere except at the endof thedivisor-are used. Inasmuch a's in addition and'multiplication the Os are not used the keyboard so presented may be considered a uni-marked keyboard and materially simrplifies the:1performance of negative calculations "member 52.

on the side 55 of the link 52.

4 as but one keyboard marking need be memorized by the operator.

As the actuating mechanisms 23 for the several denominational orders of the accumulator mechanisms are alike a description of one will suffice.

Referring to Figs. 2, 4 and 5 of the drawings,

shaft '44 extending across the machine adjacent the front end thereof. The teeth of the sector gear mesh with the teeth of the actuating pinion '4! of the accumulator mechanism which, as explained before, is coupled with the lantern wheel d2 through the medium of a pawl and ratchet mechanism. A link 55 is secured at one end to a depending arm d5 rigid with the sector gear 43 and connects the sector to the shorter arm ii! of a link in the form of a bell crank member 68 fulcrumed to the frame through the medium of a rod 59 extending across tlie'machine and supported in the frame plates. The longer arm 50 of the bell crank lever is pivotally connected at 55 to a second link in the form of a triangular The link member 52 is swingably fulcrumed to the frame through the medium of an arm 53 having one end pivoted at 54 to the member 52. The top side 55 of the link member 52 projects forwardly'below the key frame 21 to a point substantially in alignment with the 5 key of the ordinal-column-of keys with whiohit is associated.

The link members 43 and 52 together with member 53 constitute a dual difierential linkage system and provide for an improved and easier action of the keys used in adding the higher values. Furthermore, the link 50, being in the form of a bell crank lever, serves as a means of compounding the lever system for actuating the sector gears.

'Pivotally supported at 58 adjacent the forward end of the side 56 is a balanced lever 59 extending longitudinally of the ordinal row of'keys 24 and positioned for engagement by the lower end of the key stems of the keys from 1 to 5 upon depression of'those keys. Keys 6 to 9 act directly Rocking of the lever 59 relative to the side 56 in a clockwise direction (as viewed in Fig. 2) is limited by a lug 6B projecting laterally from the upper edge of the side to overlie the rear end of the lever. Provisionis'made for selectively limiting the relaitiverocking movement of .the lever in the opposite direction, such means :including a locking .dog 6'! pivotally mounted on-another side .of the link member 52 so that its notched upper end 62 may be swung .under a pin 63 projecting laterally from the lever adjacent its rear end. With the machine set for positive forms of calculation, the lever 59 constitutes in efiect an extension of the side 55 so that the keys 1 and 9 when depressed impart a progressively increasing degree of .movement to the link member 52. The notch82 engages the pin 63 to prevent the lever 59 from rotating to any extent about its pivot 53 and thus prevents the front end of the lever from fiipping upward during action of the 6 to 9 keys :during positive calculation and, as shown in Fig. 2 the upper end of the notched dog BI is spaced from the pin 63 so as to permit a slight downward movement of the rear end of the lever the movements of the lower numbered keys which engage the lever 59 forwardly of its pivotal point 58. In addition the mechanisms shown, including the two links 43 and 52, provide a more desirable distribution of the manual power required for actuation of the calculator and, incidentally, permit a desirable reduction in the size of the machine. Heretoiore levers practically a foot long, pivoted at the rear of the machine with springs to hold them suspended and connected either by racks or links to sector gears, have been used as prime movers of the denominational orders of key-driven calculating machines. The application of the keys were ranged over about half the free end of the levers, leaving about half of the rear or fulcrumed end to be boxed up in the machine casing. With such an arrangement the 9 key of course required considerably more manual power to depress than the 1 key. In my hereinbefore mentioned patent application, Serial No. 696,517, I have disclosed how the same key leverage could be obtained in a much shorter space. By the use of the dual link mechanism disclosed in the present application I find that I can provide one-fifth extra movement over and above that of the old 9 key movement, which gives a much more desirable distribution of power for the higher numbered keys. To accomplish such an increase in movement by the old scheme of leverage would require lengthening the actuating lever to about 18 inches. To achieve that extra movement in the construction disclosed in my copending application Serial No. 696,517 it would be necessary to add about 6 inches to the length of the lever shown therein to obtain the same result. The differential compound lever arrangement shown gives a greater depth of action to the higher numbered keys in positive forms of calculation like addition and multiplication and likewise increases the action of the 8 key, which adds the co-digital amount of 1 to the tens and higher orders and the complemental 2 to the units order. The action of the 1 key in all orders in either positive or negative calculations remains practically the same as in my said copending application.

When a key is depressed the motion imparted to the lever 59 and link 52 is transmitted through the link 48 to the sector gear 43 through the medium of the link 45. This motion rocks the sector gear downwardly or in a clockwise direction, as viewed in Fig. 2. Pinion 4|, with which the sector gear meshes, is correspondingly rotated but no rotation is imparted to the lantern wheel 42' because of the ratchet connection provided between pinion and the wheel. Upon return movement of the sector gear the pinion and lantern wheel are rotated an amount determined by the displacement of the sector, thus registering on the numeral wheel 22 the Value of the key depressed. Return of the. sector is effected by a tension spring 64 connected to a stud 65 rigid with the sector. Thus actual operation of the accumulator mechanism is effected uniformly irrespective of the manner in which the keys are manipulated since the operation is effected through the medium of the power stored up in the spring 64 incident to the depression of the keys and takes place upon the release of the keys.

To permit registration of complemental values for negative calculations, such as subtraction and division, provision is made for changing the leverage ratio of the lever system through which the movements of the keys are transmitted to the I the numeral wheels 22.

accumulator mechanism. More specifically, provision is made for shifting the fulcrum of the lever 59 so as substantially to reverse the extent of movement imparted to the lever system and sector 43 by the respective keys. For this purpose the lever is provided at its forward end with a fulcrum stud 66 and a latching arm 61 is pivotally supported on the sector 43 so that it may be hooked over the stud or disengaged therefrom as required. A link 68 connects the latching arm 61 with the locking dog 6| so that when one of these fulcrum elements is shifted to its active position the other is simultaneously shifted to its inactive position.

With the latching arm 61 hooked over the stud 66, as shown in Fig. 5, the locking dog 6! is consequently rocked forwardly out of the path of the pin 63 at the opposite end of the lever 59'. Depression of a key 24, accordingly, rocks the lever about the axis of the stud 66 and the lever through its pivotal connection 58 with the link member 52 rocks the latter about its swinging pivot. The action in this instance is substantially the reverse of that obtained when the looking do El is engaged since the 1 key, as controlled by the dual stop bars hereinafter described, imparts maximum displacement to the linkage while the 9 key imparts minimum displacement thereto. As previously indicated, the leverage ratios are such that the complemental values of the keys in the units order, and the codigital values in other orders are registered on Means are provided to shift the dog 6i and arm 61 upon conditioning the machine for positive or negative calculation. The mean comprise a cam slotted arm 69 fixed upon a transordinal rock shaft 10 and engaging a dolly roll Bid in the lower portion of the dog 6|. Rocking of the shaft T0 to shift the dog and arm is accomplished by depression of the proper key on the keyboard so marked as to indicate positive or negative calculation in the same manner as described in my said copending applica tion, Serial No. 696,517, through the medium of the linkage 10a connecting the shaft 10 with a transordinal rock shaft. This latter shaft is rocked upon the depression of a positive or negative key.

To insure accurate registration of the numerical values represented by the several keys 24 of each ordinal column means is provided for positively controlling the degree of actuation of the sector gear 43 upon depression of any key. This means, as herein shown, comprises a pair of stop bars H and 72 adapted to be coupled selectively with the gear sector 43 for positive and negative calculations respectively.

As more fully described in my said copending application, Serial No. 696,517, the stop bars comprise elongated sheet metal strips of angular cross-section supported below and at one side of the column of keys with one flange disposed substantially parallel to the key frame 2'! and the other flange disposed in a vertical plane. As shown in the drawings, the stop bar 12 is located below and within the angle formed by the stop bar H and both are supported for endwise sliding movement by lugs struck out from the frame members 29.

Formed on the upper flange of each of the stop bars are :a series of lugs projecting laterally for engagement with the stems 36 of the keys when the latter are depressed so as to limit the forward movement of the bars. The lugs of the stop bar H are spaced apart so that the move- Z merit-of; the bar increases progressively 'for the keys 1 to, 9, the degree of movement in each instance being such that the numerical value of each key is registered accuratel on the assoch ated numeral wheel 22. The lugs on the stop bar 52 are correspondingly spaced apart but the relative location of the lugs is such that the complementary amount of the numerical values of the keys are registered on-the numeral wheels.

To enable the stop bars to perform their control functions provision is made for selectively coupling the bars to the gear sector 53. Such selective coupling is effected through the medium of a link it! pivotally connected at one end to a control lever I la rotatably mounted on the shaft Mend resiliently connected to the sector gear 65 by means of a spring 12a for rotation therewith. The other end of the link ill is provided with a laterally projecting stud. i3 carrying a generally rectangular collar it. The collar it is adapted to fit snugly between a pair of spaced fingers i5 rigidwith the stop bar ll or alternately between a pair of spaced fingers T6 rigid with the stop bar '72. The latter fingers are formed on and projected downwardly from the vertical flange or the stop bar '52 in laterally opposite relationship while the fingers 15 are bent up from the lower edge of a tab integral with and depending upon the vertical flange of the stop bar 1 l. Thus the fingers l5 and it are disposed in a common plane and as they are so located as to be in alignment when the stop bars are in their normal positions the collar 73 may be shifted vertically into engagement with either set of fingers to couple the associated stop bar to the gear sector 55 through the medium of the control lever lid to place the sector under the control of the selected stop bar.

I claim:

1. In a key-driven calculating machine having a frame, an accumulator mechanism and an ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising: an elongated lever extending aong the column of keys, a link pivotally mounted on the frame and pivotally connected to the lever intermediate the ends thereof, means movably positioned adjacent the end of the lever remote from the link for pivotally supporting the same,

other means movably positioned adjacent the D other end of the lever for pivotally supporting the same, a sector gear engaging the accumulator mechanism, means connecting the link to the sector gear and means for moving the pivotal supports for the ends of the lever to engage either the, one or the other with the lever to provide a dual fulcrum therefor including a manually operated transordinal rock shaft pivotally supported second pivotal support engages the lever.

22. In a key-driven calculating machine having :a: frame, an accumulator mechanism and an ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising: an elongated lever extending along the column of keys for engagement thereby as the keys are depressed, a member pivotally connectedto the frame, a link pivotally connected to the member and secured to the lever, a second dinkpivoted to theframe and pivotally connected to the firstlink, a sector gear engaging thgac: cumulator mechanism and means connecting the second link to the sector gear.

3. In a key-driven calculating machine having a frame, an accumulator mechanism and an ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising: anelongated lever extending along the column of keys for engagement thereby as the keys are depressed, an arm pivoted to the frame,.

a substantially triangular link having one apex pivotally connected to the arm and having another apex secured to the lever, a fulcrumed bell crank having an arm pivotally connected t the third apex of the link, a sector gear engagingthe accumulator mechanism and a link connecting the other arm of the bell crank to the sector gear.

4. In a key-driven calculating machine having a frame, an accumulator mechanism andflan ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising an elongated lever extending along the column of keys, a member pivotally connected to the frame, a link pivotally connected to the member with said link being pivotally connected to the lever intermediate the ends thereof and with said link having a portion extending at least partially along the column of keys whereby some of the keys engage the link and the other keys engage the lever as the keys are depressed, supporting means movably positioned adjacent the end of the lever remote from said link, means for engaging the supporting means with said end of the lever pivotally to support the same, means for supporting the other end of the lever for movement with and as an extension of said portion of the link, selectively operable means for engaging one or the other of said supporting means with the lever, a second link pivoted to the frame and pivotally connected to the first link, a sector gear engaging the accumulator mechanism and means connecting the second link to the sector gear.

5. In a key-driven calculating machine having a frame, an accumulator mechanism and an ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising an elongated lever extending along the column of keys, a member pivotally connected to the frame, a link pivotally connected to the member with said link being pivotally connected to the lever intermediate the ends thereof and with said link having a portion extending at least partially along the column of keys whereby some of the keys engage the link and the other keys engage the lever as the keys are depressed, supporting means movably positioned adjacent the end of the lever remote from said link, means for engaging the supporting means with said end of the lever pivotally to support the same, means for supporting the other end of the lever for movement with and as an extension of said portion of the link, selective- 1y operable means for engaging one or the other of said supporting means with the lever, a second link in the form of a bell crank pivoted to the frame and having one arm pivotally connected to the first link, a sector gear engaging the accumulator mechanism and means connecting the other arm of the bell crank to the sector gear.

6. In a key-driven calculating machine having a frame, an accumulator mechanism and an ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising an elongated lever extending along the column of keys, a member pivotally connected to the frame, a link pivotally connected to the member with said link being pivotally connected to the lever intermediate the ends thereof and with said link having a portion extending at least partially along the column of keys whereby some of the keys engage the link and the other keys engage the lever as the keys are depressed, supporting means movably positioned adjacent the end of the lever remote from said link, means for engaging the supporting means with said end of the lever pivotally to support the same, means for supporting the other end of the lever for movement with and as an extension of said portion of the link, selectively operable means for engaging one or the other of said supporting means with the lever, a second link in the form of a bell crank pivoted to the frame and having arms of unequal length with the longer of said arms being pivotally connected to the first link, a sector gear engaging the accumulator mechanism, and means connecting the shorter arm of the bell crank to the sector gear.

7. In a key-driven calculating machine having a frame, an accumulator mechanism and an ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising an elongated lever extending along the column of keys, an arm pivoted to the frame, a substantially triangular link having one apex pivotally connected to the arm and having another apex pivotally connected to the lever intermediate the ends thereof and with said link having a portion extending at least partially along the column of keys whereby some of the keys engage the link and the other keys engage the lever as the keys are depressed, supporting means movably positioned adjacent the end of the lever remote from said link, means for engaging the supporting means with said end of the lever pivotally to support the same, means for supporting the other end of the lever for movement with and as an extension of said portion of the link, selectively operable means for engaging one or the other of said supporting means with the lever, a second link in the form of a bell crank pivoted to the frame and having an arm pivotally connected to the third apex of the link, a sector gear engaging the accumulator mechanism, and means connecting the other arm of the bell crank to the sector gear.

8. In a key-driven calculating machine having a frame, an accumulator mechanism and an ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising an elongated lever extending along the column of keys, an arm pivoted to the frame, a substantially triangular link having one apex pivotally connected to the arm and having another apex pivotally connected to the lever intermediate the ends thereof and with said link having a portion extending at least partially along the column of keys whereby some of the keys engage the link and the other keys engage the lever as the keys are depressed, supporting means movably positioned adjacent the end of the lever remote from said link, means for engaging the supporting means with said end of the lever pivotally to support the same, means for supporting the other end of the lever for movement with and as an extension of said portion of the link, selectively operable means for engaging one or the other of said supporting means with the lever, a second link in the form of sell crank pivoted to the frame and vertically spaced from the triangular link, said bell crank having arms of unequal length with the longer of said arms being pivotally connected to the third apex of the link, a sector gear engaging the accumulator mechanism, and means connecting the shorter arm of the hell crank to the sector gear.

9. In a key-driven calculating machine hava frame, an accumulator mechanism and an ordinal column of keys, means operable by said keys for actuating said accumulator mechanism comprising an arm pivoted to the a substantially triangular link having one pivotally connected to the arm and having a side extending at least partially along the column of keys for engagement thereby as the keys are depressed, a bell crank pivoted to frame and having an arm pivotally connected to another apex of the link, a sector gear engaging the ac cumulator mechanism and a link connecting the other arm of the bell crank to the sector gear.

10. In a key-driven calculating machine having a frame, an accumulator mechanism and an ordinal column of keys, m ans operable by said keys for actuating said accumulator mechanism comprising an elongated lever extending along the column of keys, a member mounted en the frame for movement in an arcuate path, a link pivotally connected to the member with said link being pivotally connected to the lever intermediate the ends thereof and with said link having a portion extending at least partially along the column of keys whereby some of the keys engage the link and the other keys engage the lever as the keys are depressed, supporting means movably positioned adjacent the end of the lever remote from said link, for engaging the supporting means with said end of the lever pivotally to support the same, means for supporting the other end of the lever for movement with and as an extension of said por tion of the link, selectively operable means for engagin one or the other of said supporting means with the lever, a second link pivoted to the frame and pivotally connected to the first link, a sector gear engaging the accumulator mechanism and means connecting the second link to the sector gear.

JOSEPH A. V. TURC'K.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 948,188 Shiek Feb. 1, 1910 1,156,600 Horton Oct. 12, 1915 1,342,459 Pasinski June 8, 1920 1,391,072 Pasinski Sept. 20, 1921 1,818,548 Friden Aug. 11, 1931 2,356,714- Webb Aug. 22, 1944 2,547,063 Turck Apr. 3, 1951 FCREIGN PATENTS Number Country Date 186,597 Switzerland May 1, 1937 

